A feature common to dental treatment equipment is a water delivery system including a flexible conduit connected between the main water supply and a hand piece including a nozzle and a manual and/or automatic control operable to cause discharge of water from the nozzle to rinse the area of the patient's mouth upon which work is being done. The water is discharged only intermittently as needed, and water stands in the system for considerable intervals.
It has been found that such systems often become contaminated, whether by micro-organisms carried in the water and attached to the conduits, or by organisms finding their way into the nozzle from the patient's mouth. It is desirable to clean such micro-organisms and other undesirable material from the system, so that it will be decontaminated and sanitary.